Conventional time based recording too often leads to . . . “this is it, the championship is on the line. The snap is good, the hold is good, the kick is up, and . . . ” And then your digital video recorder (DVR) informs you that the recording has ended. You programmed the DVR very carefully so that it would start recording on a selected channel a half hour before the big game and so that it would keep recording that selected channel for a half hour after the big game was scheduled to end. But the game went into overtime and ran extra-long. Therefore your DVR did not record the end of the most amazing game in the history of the universe. To add insult to injury, your DVR failed to record the first thirty one minutes of the season premiere of your favorite show, which was scheduled to start after the big game.
Traditional recording solutions, both audio and video, are based on recording content from a certain channel (e.g., television, radio) starting at a certain time and ending at a certain time. However, several issues have frustrated users of these traditional recording solutions. One issue, where a game or other live broadcast runs long (or short), is well known to many users. The unanticipated timing change may affect not only the big game, but also shows that follow the big game. Another issue occurs due to the lack of coordination between what time the content provider (e.g., network) thinks it is and what time the content receiver (e.g., home DVR) thinks it is. With increased usage of unmanaged networks for content delivery, this lack of coupling between provider time and receiver time can lead to a recording neither starting nor stopping on time. For example, clock drift may cause a recording device to start or stop at a time other than the actual start or stop time. An unmanaged network may be, for example, a network that does not have central control or that does not have quality of service capability.
A third issue has also frustrated users of traditional recording solutions. This third issue is a simple scheduling change, where a program that was supposed to run on Wednesday from seven to eight is moved to Thursday from eight to nine. Some attempts have been made to deal with schedule changes using updates to event information tables (EIT). However, some content delivery mechanisms (e.g., MP4 (MPEG-4 (Moving Pictures Experts Group))), do not include an EIT. Even if an EIT was included, the issue of clock drift leading to a mismatch between provider clock time and receiver clock time still exists.
Yet another issue that can frustrate recording is an unscheduled channel change. A program that was scheduled to run on television channel eight may instead run on television channel thirteen. The program may start and stop on time, but your DVR may not record the program because it moved ‘up the dial’.